You’ve got a drug test coming up. Or maybe you're just done with the brain fog and want to see what your baseline feels like again. Either way, the question is always the same: how long does it take to get clean from THC?
If you’ve spent five minutes on Reddit, you’ve probably seen a dozen different answers. One guy says he was "pissing clear" in three days after a heavy bender; another says it took him two months despite being a skinny runner. Honestly, both could be telling the truth.
THC is a stubborn molecule. Unlike alcohol, which leaves your system at a predictable rate of about one drink per hour, weed lingers. It hides. Specifically, it hides in your fat cells. That’s why there’s no universal "magic number" for detoxing, though most people are looking at a window of anywhere from 3 to 90 days.
The Science of Why THC Sticks Around
When you inhale or ingest cannabis, your body processes Delta-9-THC into various metabolites. The one drug tests actually look for is THC-COOH. This metabolite is lipid-soluble. Basically, it loves fat. While your blood clears out pretty quickly, the leftovers get tucked away in your adipose tissue (body fat).
Over time, that stored THC slowly leaks back into your bloodstream and is eventually excreted through your urine and feces. This slow-release mechanism is why heavy users often fail tests weeks after their last hit. It’s not just about what’s in your head; it's about what’s in your cells.
The Detection Windows: Urine, Blood, and Hair
The answer to "how long" depends entirely on what kind of test you're taking. Most employers go for the standard urinalysis because it’s cheap and effective. But if you’re dealing with a hair follicle test, you’re in a different ballpark entirely.
Urine Testing
For the occasional user—think someone who hits a joint once at a party—you’re usually clear in about 3 days. If you’re a moderate user (maybe three times a week), give it 5 to 7 days. Frequent, daily smokers are looking at 15 to 30 days. Now, if you are a heavy, chronic user—someone dabbing high-potency concentrates multiple times a day—you might still test positive after 45 or even 60 days. There are documented cases in the Journal of Analytical Toxicology of chronic users testing positive for over two months. It’s rare, but it happens.
Blood and Saliva
These are "active impairment" tests. They don't look for what you did last month; they look for what you did today. In blood, THC is usually gone within 24 to 48 hours, though very heavy users might show traces for a week. Saliva is even shorter, typically clearing in 12 to 24 hours.
Hair Follicle Tests
These are the boogeymen of the testing world. THC stays in your hair for roughly 90 days. Your hair grows at about half an inch per month, and labs usually test the 1.5 inches of hair closest to the scalp. It’s much harder to "flush" hair than it is to flush your bladder.
Why Your Friend Got Clean Faster Than You
Metabolism is a weird, individual thing. You could have two people who smoke the exact same amount of the same strain, and one will be clean a week earlier. Why?
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First, Body Mass Index (BMI) matters a lot. Since THC stores in fat, having a higher body fat percentage means you have a larger "storage tank" for those metabolites.
Second, frequency of use is the biggest predictor. If you're saturating your system daily, your "tank" is always full. Your body never gets a chance to fully clear the old stuff before you add more.
Third, potency has skyrocketed. The weed people smoked in the 70s was maybe 4-5% THC. Today’s flower is regularly 25%, and concentrates are 80% or higher. Your body has to work significantly harder to process those massive loads of cannabinoids.
Then there's exercise. This is a double-edged sword. Research published in Drug and Alcohol Dependence suggests that exercise can actually cause a temporary spike in blood THC levels. Why? Because you're burning fat, and that fat is releasing stored THC back into your system. If you have a test tomorrow, today is not the day for a marathon.
The Myth of the "Quick Detox"
Let's talk about the stuff you see at the back of head shops. The "Certo method," the detox drinks, the massive jugs of cranberry juice.
Do they work? Sorta, but not how you think.
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Most detox drinks don't actually "remove" THC from your body. They are masking agents. They use diuretics to make you pee more and B-vitamins to turn your urine yellow so it doesn't look diluted. They also include creatine because labs check for creatinine levels to see if you watered down your sample. If you drink a gallon of water and take a detox pill, you’re just diluting your urine. If the lab catches the low specific gravity, they’ll mark it as a "diluted" sample, which is often treated as a "fail" or requires a retest.
And please, stop drinking bleach or vinegar. It’s dangerous and doesn't work. Your liver and kidneys are the only real "detox" machines you have. You can't hack them with household cleaners.
Practical Steps to Clear Your System
If you actually want to get clean from THC, you have to play the long game. There are no shortcuts that are 100% reliable, but you can definitely help the process along.
1. Stop Immediately
This sounds obvious, but even a "tiny" hit resets your clock. Your body needs a total break to begin pulling stored metabolites out of your fat cells.
2. Hydrate, but don't drown
Drink enough water to stay healthy. You want your metabolism running at peak efficiency. However, chugging five gallons of water three weeks before a test won't help—it only helps on the day of the test to dilute the sample.
3. Focus on High-Fiber Foods
Believe it or not, about 65% of THC metabolites leave your body through your poop. Fiber binds to those metabolites in the gut and prevents them from being reabsorbed into the bloodstream (a process called enterohepatic circulation). Eat your broccoli and beans.
4. Healthy Fat Burning
If you have a few weeks, consistent cardio can help burn the fat cells where THC is hiding. But again, stop exercising 48 hours before your test. You want to keep those metabolites locked in your fat on the big day, not circulating in your urine.
5. Sleep
Your body does its best metabolic repair work while you're asleep. Skimping on rest slows down every system in your body, including your ability to process waste.
What to Expect During the Process
Getting clean isn't just about the chemistry; it's about how you feel. If you’ve been a heavy user, you’re probably going to deal with some withdrawal symptoms. It’s not like kicking opioids, but it’s definitely annoying.
Common issues include:
- Irritability and mood swings.
- Vivd, often crazy dreams (this is called "REM rebound").
- Difficulty falling asleep.
- A localized "brain fog" that lasts for the first week.
Most people start feeling significantly clearer by day 10. By day 21, the physical cravings are usually gone, and your sleep cycles should be back to normal.
The "Home Test" Strategy
Don't go into a lab blind. You can buy highly accurate THC test strips at most pharmacies or online for a few dollars. Start testing yourself once a week.
If you're still seeing a positive result after 30 days, don't panic. Some people's bodies just hold onto it longer. It’s frustrating, but it’s normal. Use the first morning pee for these tests—it's the most concentrated and will give you the "worst-case scenario" result. Once you can pass a test with your first morning urine, you're likely in the clear for any professional screening.
Actionable Steps for Today
If you need to be clean, the best time to start was yesterday. The second best time is right now.
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- Buy a pack of 15ng/mL and 50ng/mL test strips. Most labs use the 50ng/mL cutoff. If you can pass the 15ng/mL, you are golden.
- Increase your daily fiber intake to 30-35 grams. This is the most underrated way to speed up THC excretion.
- Track your BMI and activity. If you have a high body fat percentage, accept that you will need more time than the "average" window suggests.
- Avoid secondhand smoke. While rare, sitting in a "hotboxed" room can technically introduce enough THC to trip a sensitive test if you're already borderline.
Ultimately, the only guaranteed way to get clean is time. Your body is a biological system, not a sink you can just drain. Give it the tools it needs—water, fiber, and rest—and let your biology do the heavy lifting.